As is well known and understood, dual-exhaust systems for internal combustion automotive engines are of presently two types. In one, a pair of exhaust pipes are directly connected, in a straight-line arrangement, between the engine and the muffler used. In the second, the straight-line connection is augmented by a third pipe, intersecting the first two at right angles, to form an H-configuration. With this second arrangement, equal pressures are established in the two exhaust pipes, so as to increase the torque and horsepower present.
As is also well known and understood, the exhaust pipe which leaves the muffler is most oftentimes bent in various odd-shapes so as to clear the rear housing of the automotive vehicle, the power steering systems, and other control installations, in joining up with the tailpipe in channeling the exhaust flow away. Experimentation has shown that these bends add such length of piping to the exhaust system as to frequently "load-up" the engine, making it difficult to breath, causing an uneven performance, choking the engine, to give it a type of "chugging" performance. Further experimentation has shown that this "loading-up" decreased when the additional H-pipe was added to the exhaust system.